Optical testing



NOV. 16 1937. A, GOODRlCH ET AL 2,099,012

OPTICAL TESTING Filed May 29, 1935 ORS IWENT I ALBERT 6 GOOD/W677CHARLES IE Tfi/T Y ATTORNEY Patented Nov. 16, 1937 UNITED STATES PATENT;OFFICE 2,099,012 OPTICAL TESTING Albert S. Goodrich and Charles R.'Ifait, Erie, Pa., assignors to Hammermiii Paper Company, Erie,

Pa., a corporation of Pennsylvania Application May 29, 1935, Serial No.24,

This invention relates to apparatus for inspecting the surface ofvarious materials and more particularly for determination of the qualityand character of such surface.

5 Our invention finds special utility in observing 15 spectors arehighly skilled persons. However, in

addition to requiring skill and involving the human factor in properlypresenting the surface to the light a bad feature of the common practice is that it requires the light to shine directly 20 in the eyes ofthe inspector and, therefore; causes considerable glare and eye strain.By our invention controlled beams of light are caused to shinesubstantially parallel to the surface to be inspected and the materialis viewed by looking 25 down in a direction substantially perpendicularto said surface. By this method glare and eyestrain are eliminated andthe surface quality may be readily determined at a glance by anunskilled worker.

80 Further objects and advantages will be more apparent from thefollowing detailed description of one embodiment of an apparatus forcarrying out the invention..

The figure in the drawing is a longitudinal, elevational. view of anembodiment of the inspecting apparatus partly in section.

In this device a suitable source of light l and e a housing H aremounted adjacent each other on a base l2. The housing consists of alight 49 impervious bottom l3 hinged to the base at one end it andsupported near its other end in adjustable relation with said base bythe depend ing bracket l which is secured to bottom I3 and adjustablyconnected to a bracket it by a thumb 45 screw il. Bracket 86, in turn,is secured to the base. overlying the bottom member I3 is a cover it ofsuitable light impervious material and provided at its end with a slotl9 to admit light. Said 50 slot may be adjusted in size by a slidingpanel 20.

The forward end of said housing is provided with a hinged flap 2i, whichterminates a slight distance above the bottom it, and the sides of thehousing are preferably slotted as at 22 to provide for the admission ofmaterial to be inspected.

At the top of the housing and near the'forward end of the inspectingdevice there is provided an opening 23 through which the inspector mayview the material. 1 I

The adjustable light source In may consist of 5 a standard 24 clamped tothe base by the bolt and wing nut 25 and having an arcuate,substantially vertical slot 26 therein whose center of curvature is atthe hinge ll. A suitable reflector and bulb 21 or other light sourceismounted in a bracket 28 carrying a bolt 29 adapted to cooperate with theslot 26. A wing nut or thumb screw 29l may be used to hold the bolt atany desired point in the slot so that'the bracket 4 and standard will beclamped together. An as-' sembly is thus provided by which the lightsource may be raised or lowered to conform withthe angle of elevation ofthe housing and may also be rotated about the .bolt 29 to provide fortilting the light either upwardly or downwardly.

In the preferred embodiment of the apparatus, light is directed from thesource 27 through the slot |9in a direction substantially parallel tothe surface of the sheet of paper 30. The inspector places his eye atabout the point indicated at 3| 26 and looks down on the surface of saidpaper in a direction substantially perpendicular thereto. The opening 23may, if desired, be provided with a magnifying device, such as a lens,to more clearly bring out the imperfections, but this is 30 notnecessary since even such small particles as fuzz on the surface of thepaper may be seen at a glance. The device is shown tilted at a smallangle to the horizontal. This is primarily for the p rpose of making iteasier for a person standing or sitting beside the apparatus to view thematerial therein-from a comfortable position. Any convenient angle maybe used, or the testing apparatus maybe substantially parallel with thebase upon which it rests or perpendicular thereto, so long as light isadmitted in the proper relation to the surface of the sheet underinspection. By the use of a reflector concentrating the light to areasonable degree and a housing shielding this light from the operator,no glare reaches the eye of the observer. The light may be directed onthe paper at a very small angle therewith provided this is notsufiicient to produce reflection and resultant glare. The best results,however, are obtained when the light shines substantially parallel withthe surface of the material.

We do not wish to be limited by any theory of operation because theresult is clear that even 55 such small'particles as fuzz on the papersurface show up distinctly and can be readily seen. It may be thatfibres extending upwardly from the papersurface cause shadows to be castwhich can be .very easily-seen. It isquite clear that this wi1i;be thecase with relatively large projecting imperfections. I not {extendperpendicularly from the paper, but

will-be arranged at somewhatof an'angle deterv mined by the relativeslippage in the formation of the sheet so that it is probable that bydirecting the light parallel to the paper and keeping reflection at aminimum these small projections and other imperfections are selectivelyillumi'- 1-5 nated in preference to the mainsurface of the paper.

I By our invention materials may be inserted through the slot in thehousing and various imperfections on. the surface thereof can be readilyseen at a glance. bserver as is necessary in'manually holding the papertoward the light at exactly the correct angle. By the arrangement of aslot 22 and a flap 2| as illustrated in the drawing, a continu- 25 oussheet may bepassed throughthe housing and stopped from time to time forinspection. .It is also possible to inspect a sheet much larger than thearea of the-panel I! by moving the sheet around to bring the desiredportions thereof within'the range-of vision.

The use of the apparatus is not limited to inspecting paper surfaces,but may be applied to any other materials such as fabrics, metal, wood45 be,used with materials of uniform, thickness.

The provision of a variable light source, however, isvery helpful wherethe material to be inspected varies considerably in thickness. The lightsource might be located within the housing 60 I8, if desired, in such away as .to cast its rays substantially alongthe surface of the sheetbeing inspected and without being visible directly from the opening .23..will suggest themselves to persons skilled in the 55 art.

The terms and expressions which we have employed are used as terms ofdescription and not of limitation, and we have no intention, in theuseof such terms and expressions, of excluding any equivalents of thefeatures shown and described or portions thereof, but recognize thatvarious modifications are possible within the scope. of the inventionclaimed.

What we claim is: 1. Apparatus for inspecting material having arelatively fiat surface comprising, supporting means for said material,means for directing light in only one direction along said surface andsubstantially parallel thereto, means for varying the -7 angle at whichthe light strikes said surface, and means for shielding said surfacefrom other light sources but enabling said surface to be observed in adirection transverse to said light.

2. Apparatus for inspecting material having a 75 relatively flat surfacecomprising, supporting Fuzz, of course, will-ordinarily It does notrequire the skilled Numerous other changes means for sai d material, means'for directing a controlled light beam along said surface andsubstantiallyparallel thereto, means for varying the angle-at which thelight strikes said surface, and means for shielding said surface fromother light sourcesbut enabling said surface to be observed t: adirection transverse to said controlled light 3. In a device forinspecting material having a relatively fiat surface, means forsupporting said material, a light source, said light source and saidsupporting means being adjustable relative to'each other, means fordirecting light from said source along and substantially parallel 'tothesurface of said material, and means for shielding said surface fromother light sources but enabling observation of said surface in adirection substantially transverse to said light.

4. In a device' for inspecting the surfaces of paper and like materials,a relatively fiat support for su'ch'materlah'a light source, a housingoverlying said' support and so constructed and arranged as to admitlight from said source in a direction substantially parallel to .saidmaterial,

said housing having an opening in its top 'through which the surface maybe inspected, 'means for adjusting said light source relative to saidsupport and means for regulating the amount of light admitted to saidhousing.

'5. In a device for inspecting the surfaces of paper andlike materials,a relatively flat support for such material, a light source, and ahousing enclosing said support and so constructed and arranged as toadmit light from said source in a direction substantially parallel tosaid material and to exclude light from other sources, said housinghaving an opening in the side to facilitate insertion and removal of thematerial with relation to said support and having an opening in its topthrough which the surface may be inspected.

6. In a ,device for detecting imperfections in the surface of paper andthe like, a support for the material to be inspected, a housingsubstantially covering said support, means for directing a beam of lightalong and substantiallyparallel to said supporting means in only onedirection, and means for adjusting said support with respect to saiddirecting means, said housing having an inspection opening in its topthrough which the surface of the material may be viewed.

7. In a device for detecting imperfections in the surface of paperandthe-like, a support, a

housing attached to and 'substantiallycovering said support, means fordirecting a beam of light in only one direction along and substantiallyparallel to the upper surface of said supporting means, and means foradjusting said directing means with respect to said support, saidhousing having an inspection opening in its top through which thesurface of the material may be viewed.

8. Inspecting apparatus comprising a support for the material to beinspected, a housing overlying said supportprovided with means forviewing the surface of material on said support, said housing having anopening in the lower portion of an end' wall adjacent said support forthe admission of light along and substantially parallel to said support,means for varying the size ofsaid opening, a light source, means fordirecting light from said source into the housing through said opening,and means for adjusting the angle at which the directed light strikesthe surface of material on said-support.

9, a device for detecting imperfe'ctionsin, g

the surface of paper and the like, a support for paper within thehousing from a point above the the paper to be inspected, a housing oversaid support, and means for directing a beam of light support forsubstantially enclosing the same, said over the paper in a directionsubstantially paralhousing having an opening therein permitting lel tothe surface thereof be inspected and another opening permitting ob-ALBERT S. GOODRICH.

C R. TAIT.

